2-Aminopyridine → 4-Tert-butyl-phenyl-imidazo[1,2-a]pyridine

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Reaction Steps

Scheme 4 provides the synthesis of a specific intermediate following the general procedures set forth in Scheme 3, which can be further elaborated to provide compounds of the Formula (IB). 2-(4-tert-Butyl-phenyl)-5-piperazin-1-yl-imidazo[1,2-a]pyridine (7) was obtained as described in Scheme 4. 2-Aminopyridine was cyclized with 4-tert-butylphenacyl chloride to afford 2-(4-tert-butyl-phenyl-imidazo[1,2-a]pyridine (5). Lithiation followed by bromination provided a ratio of three products (6a, 70.7%; 6b, 12.3%; and 6c, 17.0%). Heating the mixture with piperazine provided (7) from (6a), which was easily separated from unreactive (6b) and (6c).

Provenance & Evidence